Last Modified: 11-29-2007 1.6 C
Service Category: Drivetrain Section: Automatic Transmission/Transaxle
Model Year: 2008 Model: Sequoia Doc ID: RM000000W83065X
Title: A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia)

DTC

P0894

Transmission Component Slipping

DTC

P2714

Pressure Control Solenoid "D" Performance (Shift Solenoid Valve SLT)

DESCRIPTION



The linear solenoid valve (SLT) controls the transmission line pressure for smooth transmission operation based on signals from the throttle position sensor and the vehicle speed sensor. The ECM adjusts the duty ratio* of the SLT solenoid valve to control the hydraulic line pressure coming from the primary regulator valve. Appropriate line pressure assures smooth shifting with varying engine outputs.

HINT:

*: The duty ratio is the ratio of the current ON time (A) to the total of the current ON and OFF time (A + B).

Duty Ratio (%) = A / (A + B) x 100

DTC No.

DTC Detection Condition

Trouble Area

P0894

The ECM detects a malfunction on SLT, S1, S2, SR, SL1, SL2 or 1-2 shift solenoid valve according to the revolution difference of the turbine and the output shaft, and also by the oil pressure. (2-trip detection logic)
  • Shift solenoid valve SLT remains open or closed
  • Shift solenoid valve S1, S2, SR, SL1 or SL2 remains open or closed
  • 1-2 shift valve is stuck
  • Valve body is blocked
  • Automatic transmission (clutch, brake or gear, etc.)

P2714

The ECM detects a malfunction on SLT (ON side) according to the revolution difference of the turbine and the output shaft, and also by the oil pressure. (2-trip detection logic)
  • Shift solenoid valve SLT remains open or closed
  • Shift solenoid valve S1, S2, SR, SL1 or SL2 remains open or closed
  • 1-2 shift valve is stuck
  • Valve body is blocked
  • Automatic transmission (clutch, brake or gear, etc.)

MONITOR DESCRIPTION

The ECM calculates the amount of heat absorbed by the friction material based on the difference in revolution (clutch slippage) between the turbine and output shaft. The ECM turns on the MIL and stores these DTCs when the amount of heat absorption exceeds the specified value.

There are two reasons that make the revolution different:

  • When the shift solenoid valve SLT remains on, oil pressure goes down and clutch engagement force decreases.
  • When the shift solenoid valve remains on or off, the gear position commanded by the ECM and the actual gear position are not the same.

NOTICE:

If you continue driving under these conditions, the clutch will burn out and the vehicle will no longer be drivable.

MONITOR STRATEGY

Related DTCs

P0894: Automatic transmission slip malfunction

P2714: Shift solenoid valve SLT/ON malfunction

Required sensors/Components

Shift solenoid valve SLT, Valve body, ATF temperature sensor, Speed sensor (NT), Speed sensor (SP2)

Frequency of operation

Continuous

Duration

P0894 ON malfunction (A): Immediately

P0894 ON malfunction (B): 0.4 seconds

P2714: Immediately

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not present

None

Turbine speed sensor circuit

Not circuit malfunction

Output speed sensor circuit

Not circuit malfunction

ATF temperature sensor "A" circuit

Not circuit malfunction

Shift solenoid valve S1 circuit

Not circuit malfunction

Shift solenoid valve S2 circuit

Not circuit malfunction

Shift solenoid valve SR circuit

Not circuit malfunction

Shift solenoid valve SL1 circuit

Not circuit malfunction

Shift solenoid valve SL2 circuit

Not circuit malfunction

Shift solenoid valve SLT circuit

Not circuit malfunction

ECT (Engine Coolant Temperature) sensor circuit

Not circuit malfunction

KCS sensor circuit

Not circuit malfunction

ETCS (Electric Throttle Control System)

Not system down

Transmission position

"D"

Duration time from shifting "N" to "D"

4 seconds or more

ECT

40°C (104°F) or more

Spark advance from max. retard timing by KCS control

0°crankshaft angle or more

Engine

Starting

TYPICAL MALFUNCTION THRESHOLDS

[P0894: ON malfunction]

When either condition below is met: OFF malfunction (A) or (B)

ON Malfunction (A)

Summation of C1 clutch heat generations

Specified value

ON Malfunction (B)

Summation of C2 clutch heat generations

Specified value

Actual gear for SLT failure judgment

Not determined

[P2714: ON malfunction]

One of the following conditions is met: ON malfunction (A), (B), (C), (D), (E), (F) or (G)

ON Malfunction (A)

Summation of C1 clutch heat generations

Specified value

ON Malfunction (B)

Shift solenoid valve S1 ON malfunction

Detected

ON Malfunction (C)

Shift solenoid valve S2 ON malfunction

Detected

ON Malfunction (D)

Shift solenoid valve SR OFF malfunction

Detected

ON Malfunction (E)

1-2 shift valve malfunction

Detected

ON Malfunction (F)

Shift solenoid valve SL1 OFF malfunction

Detected

ON Malfunction (G)

Shift solenoid valve SL2 ON malfunction

Detected

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK DTC OUTPUT (IN ADDITION TO DTCS P0894 AND P2714)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / ECT / Trouble Codes.

(e) Read the DTCs using the Techstream.

Result

Result

Proceed to
  • Only P0894 is output
  • Only P0894 and P2714 are output

A

P0894, P2714 and other DTCs are output

B

HINT:

If any other codes besides P0894 and P2714 are output, perform troubleshooting for those DTCs first.

A

2.

PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT)

NOTICE:

  • Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
  • Be careful to prevent SST hose from interfering with the exhaust pipe.
  • Perform the test with the A/C OFF.

HINT:

Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(a) Remove the test plug on the transmission case center right side and connect SST.

SST: 09992-00095

09992-00231

09992-00271

(b) Connect the Techstream to the DLC3.

(c) Start the engine and warm it up.

(d) Measure the line pressure with SST.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / ECT / Active Test.

(g) According to the display on the Techstream, perform the Active Test.

(h) Measure the line pressure.

ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Activate the Solenoid (SLT)*

Operate the shift solenoid SLT and raise line pressure

ON or OFF

HINT:

  • OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" is performed, ECM commands SLT solenoid to turn OFF)
  • ON: No action (normal operation)

[Vehicle Condition]

  • Vehicle stopped
  • Engine idling

HINT:

*: Activate the Solenoid (SLT) in the Active Test is performed to check the line pressure changes by connecting SST to the automatic transmission, which is used in the Hydraulic Test A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: HYDRAULIC TEST (2008 Sequoia) as well. Please note that the pressure values in the Active Test and Hydraulic Test are different.

OK:

The line pressure changes as specified when performing the Active Test.

OK

3.

PERFORM ACTIVE TEST USING TECHSTREAM (RUNNING TEST)

HINT:

Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(a) Connect the Techstream to the DLC3.

(b) Clear the DTC A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DTC CHECK / CLEAR (2008 Sequoia) .

(c) Enter the following menus: Powertrain / ECT / Active Test.

(d) According to the display on the Techstream, perform the Active Test.

HINT:

While driving, the shift position can be forcibly changed with the Techstream.

ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Control the Shift Position

Operate shift solenoid valve and set each shift position by yourself
  • Press "→" button: Shift up
  • Press "←" button: Shift down

Possible to check operation of shift solenoid valves

[Vehicle Condition]

50 km/h (30 mph) or less

HINT:

  • This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.
  • The 4th to 5th up-shift must be performed with the accelerator pedal released.
  • The 5th to 4th down-shift must be performed with the accelerator pedal released.
  • Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
  • The shift position commanded by the ECM is shown in the Data List display on the Techstream.

(e) Compare the ECM gear shift command and the actual gear position.

Result

ECM gear shift command

1st

2nd

3rd

4th

5th

Proceed to

Actual gear position under malfunction

Shift solenoid S1

Stuck ON

1st

2nd

2nd

1st

N*1

A

Stuck OFF

4th

3rd

3rd

4th

5th

Shift solenoid S2

Stuck ON*2

2nd

2nd

3rd

3rd

N*1

B

Stuck OFF*3

1st

1st

4th

4th

5th

Shift solenoid SL2

Stuck ON

1st

2nd

3rd

4th

N*1

C

Stuck OFF

1st

2nd

3rd

4th

5th

Shift solenoid SR

Stuck ON*4

1st

2nd

3rd

4th

5th

D

Stuck OFF*5

1st

2nd

3rd

4th

4th

Actual gear position when normal

1st

2nd

3rd

4th

5th

E

HINT:

  • *1: Neutral
  • *2: When shift solenoid S2 is stuck ON, the vehicle cannot drive in reverse.
  • *3: When shift solenoid S2 is stuck OFF, the 4th to 5th up-shift will have a large shift shock. Also, the 5th to 4th down-shift will have time lag.
  • *4: Stuck ON condition can be determined by checking if shift shock has increased excessively.
  • *5: When shift solenoid SR is stuck OFF, moving the shift lever from N to D will cause a large shift shock.
  • Gear shift can be determined by paying attention to changes in rpm.

A

4.

INSPECT SHIFT SOLENOID VALVE S1

(a) Remove the shift solenoid valve S1.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Shift solenoid valve S1 connector terminal - Shift solenoid valve S1 body

20°C (68°F)

11 to 15 Ω

(c) Connect the battery positive (+) lead to the terminal of the solenoid valve connector, and the negative (-) lead to the solenoid valve body. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

Result

Result

Proceed to

NG

A

OK

B
A

6.

INSPECT SHIFT SOLENOID VALVE S2

(a) Remove the shift solenoid valve S2.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Shift solenoid valve S2 connector terminal - Shift solenoid valve S2 body

20°C (68°F)

11 to 15 Ω

(c) Connect the battery positive (+) lead to the terminal of the solenoid valve connector, and the negative (-) lead to the solenoid valve body. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

Result

Result

Proceed to

NG

A

OK

B
A

8.

INSPECT SHIFT SOLENOID VALVE SL2

(a) Remove the shift solenoid valve SL2.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 - 2

20°C (68°F)

5.0 to 5.6 Ω

(c) Connect the battery positive (+) lead with a 21 W bulb to terminal 1 and the negative (-) lead to terminal 2 of the solenoid valve connector. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

Result

Result

Proceed to

NG

A

OK

B
A

10.

INSPECT SHIFT SOLENOID VALVE SR

(a) Remove the shift solenoid valve SR.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Shift solenoid valve SR connector terminal - Shift solenoid valve SR body

20°C (68°F)

11 to 15 Ω

(c) Connect the battery positive (+) lead to the terminal of the solenoid valve connector, and the negative (-) lead to the solenoid valve body. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

OK

11.

INSPECT SHIFT SOLENOID VALVE SL1

(a) Remove the shift solenoid valve SL1.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 - 2

20°C (68°F)

5.0 to 5.6 Ω

(c) Connect the battery positive (+) lead with a 21 W bulb to terminal 1 and the negative (-) lead to terminal 2 of the solenoid valve connector. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

Result

Result

Proceed to

NG

A

OK

B
A

13.

INSPECT SHIFT SOLENOID VALVE SLT

(a) Remove the shift solenoid valve SLT.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 - 2

20°C (68°F)

5.0 to 5.6 Ω

(c) Connect the battery positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

OK

14.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

(a) Check the transmission valve body assembly.

OK:

There are no foreign objects on each valve.

OK

15.

INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY

(a) Check the torque converter clutch assembly A750E AUTOMATIC TRANSMISSION / TRANSAXLE: TORQUE CONVERTER CLUTCH AND DRIVE PLATE: INSPECTION (2008 Sequoia) .

OK:

The torque converter clutch operates normally.

OK